Flight History
On 18 June 2015, an Airbus A380-800, registration 9V-SKI, operated by Singapore Airlines as a scheduled passenger flight from Hong Kong to Singapore. The flight crew consisted of a Pilot-in-Command (PIC) on the left seat, a Senior First Officer (SFO) on the right seat, and a Check Captain on an observer seat conducting a line check on the PIC. The SFO was the pilot flying and the PIC the pilot monitoring.
Before initiating descent into Singapore, the flight crew checked the Automatic Terminal Information Service and noted no significant weather. At 18,000 feet during descent, the crew switched on the seat belt sign and announced for cabin crew to commence before-landing checks.
Weather Radar and Avoidance
During descent from 16,000 to 7,000 feet, the weather radar detected at least one wet turbulence area within 30 nm of the aircraft, but the flight crew did not notice the magenta turbulence indication on their navigation displays. From 7,000 to 3,000 feet, the crew observed isolated cumulus clouds ahead but no thunderstorm cells. The navigation display showed mainly black with green returns, suggesting no significant weather along the approach path.
The SFO intended to fly through clear spaces between clouds and requested clearance from Air Traffic Control for a series of heading changes. Just before 6,000 feet, the SFO noticed a cumulus cloud in the aircraft's path and flew a parallel track about 3 to 4 nm to the left to avoid it. As the aircraft passed abeam the cloud, it encountered turbulence for about two seconds, causing a momentary decrease in the rate of descent.
Injuries
As a result of the turbulence, three cabin crew members fell in the aft galley of the upper deck: a Leading Steward and two Flight Stewardesses. The Leading Steward felt pain in his left hip and right knee. One Flight Stewardess injured her left knee; the other injured her right foot and hip, stating that the Leading Steward fell and landed on her right foot. After the flight, the three crew received medical treatment. One Flight Stewardess was diagnosed with a serious injury—a fracture on her right foot. The other two sustained minor injuries.
Flight Recorders
The aircraft was equipped with a Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR). Following the incident, the flight crew did not indicate in the technical log for the FDR or CVR to be removed, as they assessed the turbulence as brief and were unaware of the extent of injuries. The FDR was later removed and successfully read out, but the CVR was overwritten and unavailable for analysis.
Discussion
The flight crew's deviation of about 3 to 4 nm parallel to the cumulus cloud was insufficient to avoid the turbulence encountered. The occurrence highlights the importance of monitoring weather radar information and deviating from adverse weather by as much as practicable.